Short antibiotic therapy for legionary pneumonia

Almost 30 years have passed since the etiological role and prevalence of the previously unknown pneumonia pathogen Legionella pneumophila were determined. For several years, the etiology, epidemiology, diagnosis and treatment of legionary pneumonia have been studied in more detail, as well as the importance of other types of legionella. At the same time, it has been shown that the clinical role of Legionella goes beyond community-acquired lower respiratory infections. They have been recognized as the etiological agent of nosocomial pneumonia, surgical infections, infectious pericarditis and intraocular infections.

Historically, it was thought that pneumonia caused by these microorganisms was characterized by a moderate or severe course with a mortality rate of 10 to 15%, and with delayed administration of adequate antibiotic therapy, it was higher. The reasons for this were not entirely clear and were probably that (1) Legionella testing was only done in hospital patients with severe pneumonia and (2) co-infection with others bacteria (for example, S. pneumoniae), which in itself can cause a severe course of the disease with high mortality.

The latest generation fluoroquinolones have long been considered as potentially very effective drugs for Legionella pneumonia because of their pronounced activity against Legionella pneumophila in vitro, their ease of administration , almost the same bioequivalence when taken orally and / in the introduction and activity against most of the other agents responsible for community-acquired pneumonia. At the same time, the number of large clinical trials proving their effectiveness in the treatment of community-acquired pneumonia caused by microorganisms of the genus Legionella is insufficient.

A group of scientists from the United States conducted a retrospective study to determine the effectiveness of levofloxacin 500 mg once daily) in the treatment of patients with community-acquired Legionella pneumonia. Data from 6 clinical trials for the treatment of community-acquired pneumonia were analyzed, in which levofloxacin was compared with other drugs. The dose, route of administration and duration of treatment varied among studies. Although the design of the studies was different, the patients with identified legionellosis met the diagnostic criteria for pneumonia, and the etiology was confirmed by cultural or serological studies. Among the 1997 patients included in these studies, pneumonia caused by various species of the genus Legionella was diagnosed in 75 patients (4% of the total number of patients).

According to the results of the work carried out, more than 90% of patients with legionellosis have experienced clinical recovery 2 to 14 days after the end of treatment. No fatal outcome has been observed in patients receiving levofloxacin.

Thus, levofloxacin has been effective both at a dose of 500 mg once daily for 7 to 14 days and to 750 mg once daily for 5 days in the treatment of Legionella pneumonia.

Analysis of demographic data has also produced very interesting results. Almost a third of the patients were under the age of 55, did not smoke and did not have the concomitant illnesses commonly seen in pneumonia caused by Legionella pneumophila. In addition, in 2/3 of the patients, the disease was mild and moderate, and no deaths were observed in patients receiving levofloxacin. It is concluded that Legionnaires' disease affects not only smokers, the elderly and the immunodeficient, but that there is also the possibility of the onset of disease in a larger population. This supports the recommendations of most community-acquired pneumonia treatment guidelines for the use in ambulatory care of drugs that are active against atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila).

Thanks to the work carried out, the possibility of using shorter antibiotic therapies than those generally accepted in the etiology of Legionella of community-acquired pneumonia has been confirmed. In some patients, a 5-day course was used, recommended for uncomplicated pneumococcal pneumonia in patients with a good primary response to treatment, and the outcome of the disease, despite the etiology of legionellosis, was positive. Although there were few such cases, they represented almost 20% of patients with legionellosis. According to other sources, the use of azithromycin for a total duration of iv and oral treatment of less than 8 days was effective in 25 patients hospitalized for community-acquired pneumonia caused by Legionella pneumophila.

Somewhat contradictory results were obtained in one of the studies in which 2/3 of a small number of patients with legionary pneumonia had a satisfactory result, despite the use of cephalosporins only, which, as you know , do not affect intracellular pathogens. The analysis of a larger number of these patients will make it possible to correctly assess the results observed.